Mumlava Waterfall, Natural cascade in Harrachov, Czech Republic.

Mumlava Waterfall is a cascade on the Mumlava River in the Harrachov basin, about 2 km from Harrachov in Krkonoše National Park. The river drops roughly 8.9 m on average, up to 9.9 m from the highest pool, over granite blocks in a channel up to 10 m wide, at 760 m above sea level.

The first reliable written record comes from J. K. E. Hoser's 1804 work, which called the stream Muml. Řivnáč's Guide to the Kingdom of Bohemia, the oldest general guide to Bohemia, mentioned the waterfall in 1882. No older depictions or engravings of the waterfall are known.

The name comes from the German "murmeln", to mumble, for the sound of the falling water. Below the falls stands Mumlavská bouda, built by Count Jan Harrach because of the waterfall; it was originally a gamekeeper's lodge and now serves as an excursion restaurant. A footbridge and a viewing terrace stand by the Mumlava.

The shortest marked route runs from Harrachov's bus station along the blue trail, about 7.7 km with 163 m of ascent; alternatives start at Rýžoviště, the mining museum or the glassworks. The asphalt path is passable for wheelchairs and strollers. In summer the deep, smooth erosion pots below the falls have strong currents and are dangerous for swimming.

The flowing water has carved circular depressions into the granite rocks over time, locally known as giant pots or devil's eyes. These natural rounded formations result from the spiral motion of stones and water that slowly excavate the stone across thousands of years.